During its practical use as a mat and its periodic wash and drying processing in industrial laundries, the main physical damage that occurs to a rubber back, press molded mat is the tearing of the longitudinal border. More often than not, this tear occurs at the edge of the textile referred to as the border interface on mats. Tearing of the leading edges on mats is incidental and will not be primarily addressed by this disclosure. However, the use of the laminate to be described can be placed across the leading ends of mat to minimize tearing.
Up until the present, the constructions of mats with respect to the rubber backing has been limited to the following methods:
1. The formulation of high tear and high tensile strength rubber in a uniform thick sheet (typically 59-65 mils) which extends beyond the dimensions of the textile fabric. PA1 2. The construction of a five piece mat rubber backing which constitutes a uniform thick (typically 40-45 mils) sheet (body piece) smaller in dimensions than the textile fabric coupled with 4 strips of rubber (commonly twice as thick as the body piece) placed beneath the textile edges of the mat.
The vulcanization of rubber back, textile surfaced mats in a compression mold utilizing an inflatable diaphragm forces the longitudinal edges of the textile to embed deeper within the rubber compared to the other portion of the textile fabric. This embedding results from the unrestricted rubber movement in the border as the rubber passes through its minimum viscosity during vulcanization. The unrestrained movement of the rubber in the border allows the longitudinal edges of the textile to move deeper into the rubber backing creating a thinning of the rubber backing at the border interface. It is this thinner interface which is susceptible to tears during the mat's use and industrial laundry processing.
To avoid tearing of the rubber, mat construction has relied on the two previously described methods. Method #1 has the advantage of minimum labor requirements and minimal cycle times for curing. Also a mat is made with a uniform profile which minimizes tripping hazards. Method #2 overpowers the thinning area by doubling the rubber thickness to produce a resulting thickness comparable to that in the remaining portion of the mat. However, this five piece construction has a drawback of requiring extra labor and longer vulcanization times to cure the thicker rubber edges compared to the thinner body section beneath the textile. In addition, a mat with noticeably heightened borders is produced which is perceived to be a tripping hazard.
It is therefore an object of the invention to provide a method to produce a dust control mat which has reinforced longitudinal borders which have increased tearing strength and longer reuse life.